Polymeric vector-mediated gene transfection of MSCs for dual bioluminescent and MRI tracking in vivo

Pharmacokinetic characteristics of mesenchymal stem cells in translational challenges

Over the past two decades, mesenchymal stem/stromal cell (MSC) therapy has made substantial strides, transitioning from experimental clinical applications to commercial products. MSC therapies hold considerable promise for treating refractory and critical conditions such as acute graft-versus-host disease, amyotrophic lateral sclerosis, and acute respiratory distress syndrome. Despite recent successes in clinical and commercial applications, MSC therapy still faces challenges when used as a commercial product. Current detection methods have limitations, leaving the dynamic biodistribution, persistence in injured tissues, and ultimate fate of MSCs in patients unclear. Clarifying the relationship between the pharmacokinetic characteristics of MSCs and their therapeutic effects is crucial for patient stratification and the formulation of precise therapeutic regimens. Moreover, the development of advanced imaging and tracking technologies is essential to address these clinical challenges. This review provides a comprehensive analysis of the kinetic properties, key regulatory molecules, different fates, and detection methods relevant to MSCs and discusses concerns in evaluating MSC druggability from the perspective of integrating pharmacokinetics and efficacy. A better understanding of these challenges could improve MSC clinical efficacy and speed up the introduction of MSC therapy products to the market.

Recent Advances in Cell Sheet-Based Tissue Engineering for Bone Regeneration

In conventional bone tissue engineering, cells are seeded onto scaffolds to create three-dimensional (3D) tissues, but the cells on the scaffolds are unable to effectively perform their physiological functions due to their low density and viability. Cell sheet (CS) engineering is expected to be free from this limitation. CS engineering uses the principles of self-assembly and self-organization of endothelial and mesenchymal stem cells to prepare CSs as building blocks for engineering bone grafts. This process recapitulates the native tissue development, thus attracting significant attention in the field of bone regeneration. However, the method is still in the prebasic experimental stage in bone defect repair. To make the method clinically applicable and valuable in personalized and precision medicine, current research is focused on the preparation of multifunctionalized building blocks using CS technologies, such as 3D layered CSs containing microvascular structures. Considering the great potential of CS engineering in repairing bone defects, in this review, the types of cell technologies are first outlined. We then summarize the various types of CSs as building blocks for engineering bone grafts. Furthermore, the specific applications of CSs in bone repair are discussed. Finally, we present specific suggestions for accelerating the application of CS engineering in the clinical treatment of bone defects.

Biodistribution-based Administration of cGMP-compliant Human Umbilical Cord Mesenchymal Stem Cells Affects the Therapeutic Effect of Wound Healing

BACKGROUND

Although mesenchymal stem cells (MSCs) are used as therapeutic agents for skin injury therapy, few studies have reported the effects of dosing duration and delivery frequency on wound healing. In addition, before the clinical application of MSCs, it is important to assess whether their usage might influence tumor occurrence.

METHODS

We described the metabolic patterns of subcutaneous injection of hUC-MSCs using fluorescence tracing and qPCR methods and applied them to the development of drug delivery strategies for promoting wound healing.

RESULTS

(i) We developed cGMP-compliant hUC-MSC products with critical quality control points for wound healing; (ii) The products did not possess any tumorigenic or tumor-promoting/inhibiting ability in vivo; (iii) Fluorescence tracing and qPCR analyses showed that the subcutaneous application of hUC-MSCs did not result in safety-relevant biodistribution or ectopic migration; (iv) Reinjecting hUC-MSCs after significant consumption significantly improved reepithelialization and dermal regeneration.

CONCLUSIONS

Our findings provided a reference for controlling the quality of MSC products used for wound healing and highlighted the importance of delivery time and frequency for designing in vivo therapeutic studies.

Biocompatible Iron Oxide Nanoring-Labeled Mesenchymal Stem Cells: An Innovative Magnetothermal Approach for Cell Tracking and Targeted Stroke Therapy

Labeling stem cells with magnetic nanoparticles is a promising technique for in vivo tracking and magnetic targeting of transplanted stem cells, which is critical for improving the therapeutic efficacy of cell therapy. However, conventional endocytic labeling with relatively poor labeling efficiency and a short labeling lifetime has hindered the implementation of these innovative enhancements in stem-cell-mediated regenerative medicine. Herein, we describe an advanced magnetothermal approach to label mesenchymal stem cells (MSCs) efficiently by local induction of heat-enhanced membrane permeability for magnetic resonance imaging (MRI) tracking and targeted therapy of stroke, where biocompatible γ-phase, ferrimagnetic vortex-domain iron oxide nanorings (γ-FVIOs) with superior magnetoresponsive properties were used as a tracer. This approach facilitates a safe and efficient labeling of γ-FVIOs as high as 150 pg of Fe per cell without affecting the MSCs proliferation and differentiation, which is 3.44-fold higher than that by endocytosis labeling. Such a high labeling efficiency not only enables the ultrasensitive magnetic resonance imaging (MRI) detection of sub-10 cells and long-term tracking of transplanted MSCs over 10 weeks but also endows transplanted MSCs with a magnetic manipulation ability in vivo. A proof-of-concept study using a rat stroke model showed that the labeled MSCs facilitated MRI tracking and magnetic targeting for efficient replacement therapy with a significantly reduced dosage of 5 × 10⁴ transplanted cells. The findings in this study have demonstrated the great potential of the magnetothermal approach as an efficient labeling technique for future clinical usage.

Molecular imaging nanoprobes for theranostic applications

As a non-invasive imaging monitoring method, molecular imaging can provide the location and expression level of disease signature biomolecules in vivo, leading to early diagnosis of relevant diseases, improved treatment strategies, and accurate assessment of treating efficacy. In recent years, a variety of nanosized imaging probes have been developed and intensively investigated in fundamental/translational research and clinical practice. Meanwhile, as an interdisciplinary discipline, this field combines many subjects of chemistry, medicine, biology, radiology, and material science, etc. The successful molecular imaging not only requires advanced imaging equipment, but also the synthesis of efficient imaging probes. However, limited summary has been reported for recent advances of nanoprobes. In this paper, we summarized the recent progress of three common and main types of nanosized molecular imaging probes, including ultrasound (US) imaging nanoprobes, magnetic resonance imaging (MRI) nanoprobes, and computed tomography (CT) imaging nanoprobes. The applications of molecular imaging nanoprobes were discussed in details. Finally, we provided an outlook on the development of next generation molecular imaging nanoprobes.

Nanotechnology-Assisted Cell Tracking

The usefulness of nanoparticles (NPs) in the diagnostic and/or therapeutic sector is derived from their aptitude for navigating intra- and extracellular barriers successfully and to be spatiotemporally targeted. In this context, the optimization of NP delivery platforms is technologically related to the exploitation of the mechanisms involved in the NP-cell interaction. This review provides a detailed overview of the available technologies focusing on cell-NP interaction/detection by describing their applications in the fields of cancer and regenerative medicine. Specifically, a literature survey has been performed to analyze the key nanocarrier-impacting elements, such as NP typology and functionalization, the ability to tune cell interaction mechanisms under in vitro and in vivo conditions by framing, and at the same time, the imaging devices supporting NP delivery assessment, and consideration of their specificity and sensitivity. Although the large amount of literature information on the designs and applications of cell membrane-coated NPs has reached the extent at which it could be considered a mature branch of nanomedicine ready to be translated to the clinic, the technology applied to the biomimetic functionalization strategy of the design of NPs for directing cell labelling and intracellular retention appears less advanced. These approaches, if properly scaled up, will present diverse biomedical applications and make a positive impact on human health.

Comparison of the treatment efficacy of umbilical mesenchymal stem cell transplantation via renal subcapsular and parenchymal routes in AKI-CKD mice

Background

Mesenchymal stem cells (MSCs) have emerged as a promising cell-based therapy for acute kidney injury (AKI). However, the optimal route of MSC transplantation remains controversial, and there have been no comparisons of the therapeutic benefits of MSC administration through different delivery routes.

Methods

In this study, we encapsulated MSCs into a collagen matrix to help achieve local MSC retention in the kidney and assessed the survival of MSCs in vitro and in vivo. After transplanting collagen matrix-encapsulated-MSCs (Col-MSCs) under the renal capsule or into the parenchyma using the same cell dose and suspension volume in an ischemia/reperfusion injury model, we evaluated the treatment efficacy of two local transplantation routes at different stages of AKI.

Results

We found that Col-MSCs could be retained in the kidney for at least 14 days. Both local MSC therapies could reduce tubular injury, promote the proliferation of renal tubular epithelial cells on Day 3 and alleviate renal fibrosis on Day 14 and 28. MSC transplantation via the subcapsular route exerts better therapeutic effects for renal functional and structural recovery after AKI than MSC administration via the parenchymal route.

Conclusions

Subcapsular MSC transplantation may be an ideal route of MSC delivery for AKI treatment, and collagen I can provide a superior microenvironment for cell–cell and cell–matrix interactions to stabilize the retention rate of MSCs in the kidney.

Supplementary Information

The online version contains supplementary material available at 10.1186/s13287-022-02805-3.

Nanoparticles for Stem Cell Tracking and the Potential Treatment of Cardiovascular Diseases

Stem cell-based therapies have been shown potential in regenerative medicine. In these cells, mesenchymal stem cells (MSCs) have the ability of self-renewal and being differentiated into different types of cells, such as cardiovascular cells. Moreover, MSCs have low immunogenicity and immunomodulatory properties, and can protect the myocardium, which are ideal qualities for cardiovascular repair. Transplanting mesenchymal stem cells has demonstrated improved outcomes for treating cardiovascular diseases in preclinical trials. However, there still are some challenges, such as their low rate of migration to the ischemic myocardium, low tissue retention, and low survival rate after the transplantation. To solve these problems, an ideal method should be developed to precisely and quantitatively monitor the viability of the transplanted cells in vivo for providing the guidance of clinical translation. Cell imaging is an ideal method, but requires a suitable contrast agent to label and track the cells. This article reviews the uses of nanoparticles as contrast agents for tracking MSCs and the challenges of clinical use of MSCs in the potential treatment of cardiovascular diseases.

Mesenchymal Stem Cells Engineered by Nonviral Vectors: A Powerful Tool in Cancer Gene Therapy

Due to their "tumor homing" and "immune privilege" characteristics, the use of mesenchymal stem cells (MSCs) has been proposed as a novel tool against cancer. MSCs are genetically engineered in vitro and then utilized to deliver tumoricidal agents, including prodrugs and bioactive molecules, to tumors. The genetic modification of MSCs can be achieved by various vectors, and in most cases viral vectors are used; however, viruses may be associated with carcinogenesis and immunogenicity, restricting their clinical translational potential. As such, nonviral vectors have emerged as a potential solution to address these limitations and have gradually attracted increasing attention. In this review, we briefly revisit the current knowledge about MSC-based cancer gene therapy. Then, we summarize the advantages and challenges of nonviral vectors for MSC transfection. Finally, we discuss recent advances in the development of new nonviral vectors, which have provided promising strategies to overcome obstacles in the gene modulation of MSCs.

A reduction and pH dual-sensitive nanodrug for targeted theranostics in hepatocellular carcinoma

Sorafenib (SF) is the first drug demonstrated to improve the survival of patients diagnosed with advanced-stage hepatocellular carcinoma (HCC). However, its clinical application is limited by the poor oral bioavailability and severe side effects. In this study, a multifunctional micellar nanodrug was developed for simultaneous HCC-targeted delivery of SF and tumor detection with magnetic resonance imaging (MRI). The micellar nanodrug incorporating SF and superparamagnetic iron oxide nanoparticles (SPIONs) was prepared from a diblock copolymer of monomethoxyl poly(ethylene glycol) and poly(N-(2-aminoethanethiol-co-2-aminoethyldiisopropylamine) aspartamide) and then decorated with anti-glypican-3 antibody (Ab_GPC3). Owing to the small size, weak positive charge and Ab_GPC3-mediated active targeting to HCC cells, the nanodrug exhibited an easy cellular uptake and enhanced tumor accumulation. The prominent reduction and pH dual-sensitivity allowed the nanodrug to rapidly release SF inside cancer cells via responding to the cytoplasmic glutathione and lysosomal acidity. The nanodrug not only significantly improved the anticancer effects of SF in hepatoma treatment but also facilitated a noninvasive tumor detection and monitoring of in vivo drug delivery by MRI, which revealed its great potential as a promising theranostic system.

Improved Nucleic Acid Therapy with Advanced Nanoscale Biotechnology

Due to a series of systemic and intracellular obstacles in nucleic acid (NA) therapy, including fast degradation in blood, renal clearance, poor cellular uptake, and inefficient endosomal escape, NAs may need delivery methods to transport to the cell nucleus or cytosol to be effective. Advanced nanoscale biotechnology-associated strategies, such as controlling the particle size, charge, drug loading, response to environmental signals, or other physical/chemical properties of delivery carriers, have provided great help for the in vivo and in vitro delivery of NA therapeutics. In this review, we introduce the characteristics of different NA modalities and illustrate how advanced nanoscale biotechnology assists NA therapy. The specific features and challenges of various nanocarriers in clinical and preclinical studies are summarized and discussed. With the help of advanced nanoscale biotechnology, some of the major barriers to the development of NA therapy will eventually be overcome in the near future.

A microfluidic 3D hepatocyte chip for hepatotoxicity testing of nanoparticles

Aim: To develop a practical microfluidic 3D hepatocyte chip for hepatotoxicity testing of nanoparticles using proof of concept studies providing first results of the potential hepatotoxicity of superparamagnetic iron oxide nanoparticles (SPION) under microfluidic conditions. Methods: A microfluidic 3D hepatocyte chip with three material layers, which contains primary rat hepatocytes, has been fabricated and tested using different concentrations (50, 100 and 200 μg/ml) of SPION in 3-day (short-term) and 1-week (long-term) cultures. Results: Compared with standard well plates, the hepatocyte chip with flow provided comparable viability and significantly higher liver-specific functions, up to 1 week. In addition, the chip recapitulates the key physiological responses in the hepatotoxicity of SPION. Conclusion: Thus, the developed 3D hepatocyte chip is a robust and highly sensitive platform for investigating hepatotoxicity profiles of nanoparticles.

ZnAs@SiO2 nanoparticles as a potential anti-tumor drug for targeting stemness and epithelial-mesenchymal transition in hepatocellular carcinoma via SHP-1/JAK2/STAT3 signaling

Rationale: Current therapies for hepatocellular carcinoma (HCC) are hampered by treatment failure and recurrence due to the remaining treatment-resistant liver cancer stem cells (CSCs). Stemness and epithelial-mesenchymal transition (EMT) are regarded as two fundamental characteristics of liver CSCs necessary for cancer progression; thus, drugs that simultaneously target both characteristics should prove effective in eliminating HCC and impeding recurrence. In this study, we developed new arsenic trioxide (ATO)-based nanoparticles (NPs), which are expected to be more effective than the current HCC therapy, and explored their potential mechanism.

Methods: A “one-pot” reverse emulsification approach was employed to prepare the ZnAs@SiO₂ NPs. HCC cell lines, MHCC97L and Hep3b, were used to analyze the antitumor activity of ZnAs@SiO₂ NPs in vitro and in vivo by quantifying cell growth and metastasis as well as to study the effect on stemness and EMT. SHP-1 siRNA was used to validate the role of the SHP-1/JAK2/STAT3 signaling pathway in mediating inhibition of stemness and EMT by ZnAs@SiO₂.

Results: Compared with the current ATO treatment, ZnAs@SiO₂ NPs promoted apoptosis and significantly inhibited proliferation, migration, and invasion of both MHCC97L and Hep3b cells. In the in vivo assay, ZnAs@SiO₂ NPs inhibited tumor growth by 2.2-fold and metastasis by 3.5-fold as compared to ATO. The ZnAs@SiO₂ NPs also inhibited tumor spheroid formation in vitro and tumor initiation in vivo and induced significant changes in the expression of stemness markers (CD133, Sox-2, and Oct-4) and EMT markers (E-cadherin, Vimentin, and Slug) both in vitro and in vivo. These effects of ZnAs@SiO₂ that correlated with prognosis of HCC were mediated by the SHP-1/JAK2/STAT3 signaling.

Conclusions: ZnAs@SiO₂ NPs can effectively suppress tumor initiation, growth, metastasis, and inhibit stemness and EMT through regulation of SHP-1/JAK2/STAT3 signaling pathway in liver cancer cells in vitro and in vivo. Thus, ZnAs@SiO₂ NPs have immense potential for HCC treatment in the future.

Ferrimagnetic Nanochains‐Based Mesenchymal Stem Cell Engineering for Highly Efficient Post‐Stroke Recovery

Unsatisfactory post‐stroke recovery has long been a negative factor in the prognosis of ischemic stroke due to the lack of pharmacological treatments. Mesenchymal stem cells (MSCs)‐based therapy has recently emerged as a promising strategy redefining stroke treatment; however, its effectiveness has been largely restricted by insufficient therapeutic gene expression and inadequate cell numbers in the ischemic cerebrum. Herein, a non‐viral and magnetic field‐independent gene transfection approach is reported, using magnetosome‐like ferrimagnetic iron oxide nanochains (MFIONs), to genetically engineer MSCs for highly efficient post‐stroke recovery. The 1D MFIONs show efficient cellular uptake by MSCs, which results in highly efficient genetic engineering of MSCs to overexpress brain‐derived neurotrophic factor for treating ischemic cerebrum. Moreover, the internalized MFIONs promote the homing of MSCs to the ischemic cerebrum by upregulating CXCR4. Consequently, a pronounced recovery from ischemic stroke is achieved using MFION‐engineered MSCs in a mouse model.

Dissecting the Pharmacodynamics and Pharmacokinetics of MSCs to Overcome Limitations in Their Clinical Translation

Recently, mesenchymal stromal stem cells (MSCs) have been proposed as therapeutic agents because of their promising preclinical features and good safety profile. However, their introduction into clinical practice has been associated with a suboptimal therapeutic profile. In this review, we address the biodistribution of MSCs in preclinical studies with a focus on the current understanding of the pharmacodynamics (PD) and pharmacokinetics (PK) of MSCs as key aspects to overcome unsatisfactory clinical benefits of MSC application. Beginning with evidence of MSC biodistribution and highlighting PK and PD factors, a new PK-PD model is also proposed. According to this theory, MSCs and their released factors are key players in PK, and the efficacy biomarkers are considered relevant for PD in more predictive preclinical investigations. Accounting for the PK-PD relationship in MSC translational research and proposing new models combined with better biodistribution studies could allow realization of the promise of more robust MSC clinical translation.

MRI-visible and pH-sensitive micelles loaded with doxorubicin for hepatoma treatment

A novel pH-sensitive micelle was constructed to efficiently co-deliver SPIONs and doxorubicin for cancer theranostic application.

In vivo long-term investigation of tumor bearing mKate2 by an in-house fluorescence molecular imaging system

Background

Optical imaging is one of the most common, low-cost imaging tools used for investigating the tumor biological behavior in vivo. This study explores the feasibility and sensitivity of a near infrared fluorescent protein mKate2 for a long-term non-invasive tumor imaging in BALB/c nude mice, by using a low-power optical imaging system.

Methods

In this study, breast cancer cell line MDA-MB-435s expressing mKate2 and MDA-MB-231 expressing a dual reporter gene firefly luciferase (fLuc)-GFP were used as cell models. Tumor cells were implanted in different animal body compartments including subcutaneous, abdominal and deep tissue area and closely monitored in real-time. A simple and low-power optical imaging system was set up to image both fluorescence and bioluminescence in live animals.

Results

The presence of malignant tissue was further confirmed by histopathological assay. Considering its lower exposure time and no need of substrate injection, mKate2 is considered a superior choice for subcutaneous imaging compared with fLuc. On the contrary, fLuc has shown to be a better option when monitoring the tumor in a diffusive area such as abdominal cavity. Furthermore, both reporter genes have shown good stability and sensitivity for deep tissue imaging, i.e. tumor within the liver. In addition, fLuc has shown to be an excellent method for detecting tumor cells in the lung.

Conclusions

The combination of mKate2 and fLuc offers a superior choice for long-term non-invasive real-time investigation of tumor biological behavior in vivo.

Transplanting Mesenchymal Stem Cells for Treatment of Ischemic Stroke

Stroke is a major disease that leads to high mortality and morbidity. Given the ageing population and the potential risk factors, the prevalence of stroke and socioeconomic burden associated with stroke are expected to increase. During the past decade, both prophylactic and therapeutic strategies for stroke have made significant progress. However, current therapies still cannot adequately improve the outcomes of stroke and may not apply to all patients. One of the significant advances in modern medicine is cell-derived neurovascular regeneration and neuronal repair. Progress in stem cell biology has greatly contributed to ameliorating stroke-related brain injuries in preclinical studies and demonstrated clinical potential in stroke treatment. Mesenchymal stem cells (MSCs) have the differentiating potential of chondrocytes, adipocytes, and osteoblasts, and they have the ability to transdifferentiate into endothelial cells, glial cells, and neurons. Due to their great plasticity, MSCs have drawn much attention from the scientific community. This review will focus on MSCs, stem cells widely utilized in current medical research, and evaluate their effect and potential of improving outcomes in ischemic stroke.

Dose-, treatment- and time-dependent toxicity of superparamagnetic iron oxide nanoparticles on primary rat hepatocytes

AIM

As a first study in literature, to investigate concentration-dependent (0-400 μg/ml) and exposure-dependent (single dosing vs cumulative dosing) effects of superparamagnetic iron oxide nanoparticles (d = 10 nm) on primary rat hepatocytes in a time-dependent manner.

MATERIALS & METHODS

Sandwich-cultured hepatocyte model was used to evaluate viability, hepatocyte specific functions and reactive oxygen species level.

RESULTS

In terms of all parameters, generally statistically more significant effects were observed in a concentration- and time-dependent manner. In terms of hepatocyte-specific functions, cumulative dosing caused significantly (p < 0.05) more deleterious effects at 48th hour.

CONCLUSION

A combination of various biomarkers should be employed for the evaluation of the effect of superparamagnetic iron oxide nanoparticles on liver, and each biomarker should be analyzed in a time- and exposure-dependent manner.

Cell tracking, survival, and differentiation capacity of adipose-derived stem cells after engraftment in rat tissue

Adipose tissue is an important source of adipose derived stem cells (ADSCs). These cells have the potential of being used for certain therapies, in which the main objective is to recover the function of a tissue/organ affected by a disease. In order to contribute to repair of the tissue, these cells should be able to survive and carry out their functions in unfavorable conditions after being transplanted. This process requires a better understanding of the biology involved: such as the time cells remain in the implant site, how long they stay there, and whether or not they differentiate into host tissue cells. This report focuses on these questions. ADSC were injected into three different tissues (substantia nigra, ventricle, liver) and they were tracked in vivo with a dual GFP-Luc reporter system. The results show that ADSCs were able to survive up to 4 months after the engraftment and some of them started showing resident cell tissue phenotype. These results demonstrate their long-term capacity of survival and differentiation when injected in vivo.

Tracking of transplanted human umbilical cord-derived mesenchymal stem cells labeled with fluorescent probe in a mouse model of acute lung injury

The aim of the present study was topreliminarily visualize the distribution of humanumbilical cord-derived-mesenchymal stem cells (hUC-MSCs) in treating acute lung injury (ALI) using a targeted fluorescent technique. Anovel fluorescent molecule probe was first synthesized via the specific binding of antigen and antibody in vitro to label the hUC-MSCs. Two groups of mice, comprising a normal saline (NS)+MSC group and lipopolysaccharide (LPS)+MSC group, were subjected to optical imaging. At 4 h following ALI mouse model construction, the labeled hUC-MSCs were transplanted into the mice in the NS+MSC group and LPS+MSC group by tail vein injection. The mice were sacrificed 30 min, 1 day, 3 days and 7 days following injection of the labeled hUC-MSCs, and the lungs, heart, spleen, kidneys and liver were removed. The excised lungs, heart, spleen, kidneys and liver were then detected on asmall animal fluorescent imager. The fluorescent results showed that the signal intensity in the lungs of the LPS+MSC group was significantly higher, compared with that of the NS+MSC group at 30 min (3.53±0.06×10⁻⁴, vs. 1.95±0.05×10⁻⁴ scaled counts/sec), 1 day (36.20±0.77×10⁻⁴, vs. 23.45±0.43×10⁻⁴ scaled counts/sec), 3 days (11.83±0.26×10⁻⁴, vs. 5.39±0.10×10⁻⁴ scaled counts/sec), and 7 days (3.14±0.04×10⁻⁴, vs. 0.00±0.00×10⁻⁴ scaled counts/sec; all P<0.05). The fluorescence intensity in the liver of the LPS+MSC group, vs. NS+MSC group was measured at 30 min (0.00±0.00×10⁻⁴, vs. 0.00±0.00×10⁻⁴ scaled counts/sec); 1 day (5.53±0.08×10⁻⁴, vs. 5.44±0.16×10⁻⁴ scaled counts/sec); 3 days (0.00±0.00×10⁻⁴, vs. 8.67±0.05×10⁻⁴ scaled counts/sec); 7 days (0.00±0.00×10⁻⁴, vs. 0.00±0.00×10⁻⁴ scaled counts/sec). The signal intensity of the heart, spleen and kidneys was minimal. In conclusion, the novel targeted fluorescence molecular probe was suitable for tracking the distribution processes of hUC-MSCs in treating ALI.

Versatile Supermolecular Inclusion Complex Based on Host-Guest Interaction for Targeted Gene Delivery

A facile and targeted gene delivery system was prepared by conjugating β-cyclodextrin modified polyethylenimine (PEI-CD) and adamantyl peptide (AdGRGDS) based on host-guest interaction. With the rational design between PEI-CD and AdGRGDS, the PEI-CD/AdGRGDS gene delivery system showed excellent DNA binding capability and exhibited good ability to compact DNA into uniform spherical nanoparticles. In vitro luciferase assay showed that gene expression transfected by PEI-CD/AdGRGDS was stronger than that by PEI-CD in HeLa cells, whereas gene expression transfected by PEI-CD/AdGRGDS and PEI-CD was similar to each other in COS7 cells. Internalization of complexes was qualitatively studied using a confocal laser scanning microscope (CLSM) and quantitatively analyzed by flow cytometry, respectively, and targeting specificity was also evaluated by CLSM. Results of CLSM and flow cytometry indicated that PEI-CD/AdGRGDS had good targeting specificity to tumor cells with integrin αvβ3 overexpression. To further evaluate the targeting specificity and transfection efficiency in vivo, a rat model with murine hepatic carcinoma cell line H22 was used. PEI-CD/AdGRGDS showed stronger gene expression efficiency than PEI-CD via in vivo transfection of pORF-LacZ and pGL-3 plasmids after subcutaneous injection. Interestingly, PEI-CD/AdGRGDS also showed high targeting specificity and transfection distribution to tumor xenograft after tail-vein injection. In vitro and in vivo assays highlighted the importance of GRGDS targeting specificity to tumor cells with integrin αvβ3 overexpression and demonstrated that the PEI-CD/AdGRGDS gene delivery system would have great potential for targeted tumor therapy.

Light-Controlled BMSC Sheet-Implant Complexes with Improved Osteogenesis via an LRP5/β-Catenin/Runx2 Regulatory Loop

The combination of bone marrow mesenchymal stem cell (BMSC) sheets and titanium implants (BMSC sheet-implant complexes) can accelerate osseointegration. However, methods of fabricating BMSC sheet-implant complexes are quite limited, and the survival of BMSC sheet-implant complexes is one of the key barriers. Here, we show that a light-controlled fabricating system can generate less injured BMSC sheet-implant complexes with improved viability and osteogenesis and that noninvasive monitoring of the viability of BMSC sheet-implant complexes using a lentiviral delivery system is feasible. Enhanced green fluorescent protein- and luciferase-expressing BMSC sheets were used to track the viability of BMSC sheet-implant complexes in vivo. The experiments of micro-computed tomography analysis and hard tissue slices were performed to evaluate the osteogenic ability of BMSC sheet-implant complexes in vivo. The results showed that BMSC sheet-implant complexes survived for almost 1 month after implantation. Notably, BMSC sheet-implant complexes fabricated by the light-controlled fabricating system had upregulating expression levels of low-density lipoprotein-receptor-related protein 5 (LRP5), β-catenin, and runt-related transcription factor 2 (Runx2) compared to the complexes fabricated by mechanical scraping. Furthermore, we found that Runx2 directly bound to the rat LRP5 promoter and the LRP5/β-catenin/Runx2 regulatory loop contributed to the enhancement of the osseointegrating potentials. In this study, we successfully fabricated BMSC sheet-implant complexes with improved viability and osteogenesis and established a feasible, noninvasive, and continuous method for tracking BMSC sheet-implant complexes in vivo. Our findings lay the foundation for the application of BMSC sheet-implant complexes in vivo and open new avenues for engineered BMSC sheet-implant complexes.

Hepatocellular Carcinoma Cells Carrying a Multimodality Reporter Gene for Fluorescence, Bioluminescence, and Magnetic Resonance Imaging In Vitro and In Vivo

RATIONALE AND OBJECTIVES

The study aimed to evaluate the feasibility of imaging or tracking hepatocellular carcinoma cells by modifying these cells to carry a multimodality reporter gene, enabling fluorescence, bioluminescence, and magnetic resonance imaging (MRI) in vitro and in vivo.

MATERIALS AND METHODS

HepG2 cells were labeled with the enhanced green fluorescent protein (EGFP)/luciferase2/ferritin-the multimodality reporter gene (labeled HepG2 cells). The labeled and unlabeled HepG2 cells were cultured in vitro and then injected subcutaneously into mice as a hepatoma model in vivo. The expressions of EGFP, luciferase2, and ferritin in HepG2 cell suspensions and hepatoma model were investigated using fluorescence, bioluminescence, and MRI.

RESULTS

Individual HepG2 cells expressing EGFP were identified under blue laser excitation. The linear coefficient between the optical signal intensity of luciferase2 and the number of labeled cells was 0.993. MRI was used to distinguish the T2* signal of 2 × 10⁷ cells/mL between the labeled (6.67 ± 1.88 ms) and unlabeled cells (10.66 ± 2.22 ms) (P = 0.034). In vivo, individual HepG2 cells expressing EGFP in frozen sections were observed. Labeled cells expressing luciferase2 have been detected since the second day after injection, and the bioluminescence increased with the tumor size. The T2* signal was significantly different between the labeled (6.04 ± 1.60 ms) and unlabeled cells (17.06 ± 2.17 ms) (P <0.001).

CONCLUSIONS

A multimodality reporter gene consisting of EGFP, luciferase2, and ferritin was successfully integrated into the HepG2 cell genome via a lentiviral vector and was highly expressed in the daughter cells. These cells could be detected by fluorescence, bioluminescence, and MRI in vitro and in vivo.

Efficient delivery of C/EBP beta gene into human mesenchymal stem cells via polyethylenimine-coated gold nanoparticles enhances adipogenic differentiation

The controlled differentiation of stem cells via the delivery of specific genes encoding appropriate differentiation factors may provide useful models for regenerative medicine and aid in developing therapies for human patients. However, the majority of non-viral vectors are not efficient enough to manipulate difficult-to-transfect adult human stem cells in vitro. Herein, we report the first use of 25 kDa branched polyethylenimine-entrapped gold nanoparticles (AuPEINPs) and covalently bound polyethylenimine-gold nanoparticles (AuMUAPEINPs) as carriers for efficient gene delivery into human mesenchymal stem cells (hMSCs). We determined a functional application of these nanoparticles by transfecting hMSCs with the C/EBP beta gene, fused to EGFP, to induce adipogenic differentiation. Transfection efficacy with AuPEINPs and AuMUAPEINPs was 52.3% and 40.7%, respectively, which was 2.48 and 1.93 times higher than that by using Lipofectamine 2000. Luciferase assay results also demonstrated improved gene transfection efficiency of AuPEINPs/AuMUAPEINPs over Lipofectamine 2000 and polyethylenimine. Overexpression of exogenous C/EBP beta significantly enhanced adipogenesis in hMSCs as indicated by both of Oil Red O staining and mRNA expression analyses. Nanoparticle/DNA complexes exhibited favorable cytocompatibility in hMSCs. Taken together, AuPEINPs and AuMUAPEINPs potentially represent safe and highly efficient vehicles for gene delivery to control hMSC differentiation and for therapeutic gene delivery applications.

Poly (dopamine) coated superparamagnetic iron oxide nanocluster for noninvasive labeling, tracking, and targeted delivery of adipose tissue-derived stem cells

Tracking and monitoring of cells in vivo after transplantation can provide crucial information for stem cell therapy. Magnetic resonance imaging (MRI) combined with contrast agents is believed to be an effective and non-invasive technique for cell tracking in living bodies. However, commercial superparamagnetic iron oxide nanoparticles (SPIONs) applied to label cells suffer from shortages such as potential toxicity, low labeling efficiency, and low contrast enhancing. Herein, the adipose tissue-derived stem cells (ADSCs) were efficiently labeled with SPIONs coated with poly (dopamine) (SPIONs cluster@PDA), without affecting their viability, proliferation, apoptosis, surface marker expression, as well as their self-renew ability and multi-differentiation potential. The labeled cells transplanted into the mice through tail intravenous injection exhibited a negative enhancement of the MRI signal in the damaged liver-induced by carbon tetrachloride, and subsequently these homed ADSCs with SPIONs cluster@PDA labeling exhibited excellent repair effects to the damaged liver. Moreover, the enhanced target-homing to tissue of interest and repair effects of SPIONs cluster@PDA-labeled ADSCs could be achieved by use of external magnetic field in the excisional skin wound mice model. Therefore, we provide a facile, safe, noninvasive and sensitive method for external magnetic field targeted delivery and MRI based tracking of transplanted cells in vivo.

Functional biomedical hydrogels for in vivo imaging

In vivo imaging of biomedical hydrogels enables real-time and non-invasive visualization of the status of structure and function of hydrogels.

Optimization of mesenchymal stem cells (MSCs) delivery dose and route in mice with acute liver injury by bioluminescence imaging

PURPOSE

Both experimental and initial clinical studies have shown the therapeutic potential of mesenchymal stem cells (MSCs) in liver disease. Noninvasive tracking of MSCs could facilitate its clinical translation. The purpose of this study was to optimize MSCs delivery dose and route in mice with acute liver injury using bioluminescence imaging (BLI) to track the cells.

PROCEDURES

MSCs were labeled with the Luc2-mKate2 dual-fusion reporter gene (MSCs-R). The fate of MSCs-R was tracked through in vivo BLI after administration of different doses or delivery through different routes.

RESULTS

When delivered via the superior mesenteric vein (SMV), the high-dose (1.0 × 10(6) and 5.0 × 10(5)) group mice demonstrated high liver BLI signal but also had lethal portal vein embolization (PVE). By contrast, no PVE and its related death occurred in the low-dose (2.5 × 10(5)) group mice. Thus, 2.5 × 10(5) is the optimal delivery dose. Three delivery routes, i.e., inferior vena cava (IVC), SMV, and intrahepatic (IH) injection, were also systematically compared. After IVC infusion, MSCs-R were quickly trapped inside the lungs, and no detectable homing to the liver and other organs was observed. By IH injection, lung entrapment was bypassed, but MSCs-R distribution was only localized in the injection region of the liver. By contrast, after SMV infusion, MSCs-R were dispersedly distributed and stayed as long as 7-day posttransplantation in the liver. The in vivo imaging results were further validated by ex vivo imaging, digital subtraction angiography (DSA), and tissue analysis. Therefore, SMV is the optimal MSCs delivery route for liver disease.

CONCLUSIONS

Collectively, BLI, which could dynamically and quantitatively track cellular location and survival, is useful in determining MSCs transplantation parameters.

Galectin-1-secreting neural stem cells elicit long-term neuroprotection against ischemic brain injury

Galectin-1 (gal-1), a special lectin with high affinity to β-galactosides, is implicated in protection against ischemic brain injury. The present study investigated transplantation of gal-1-secreting neural stem cell (s-NSC) into ischemic brains and identified the mechanisms underlying protection. To accomplish this goal, secretory gal-1 was stably overexpressed in NE-4C neural stem cells. Transient cerebral ischemia was induced in mice by middle cerebral artery occlusion for 60 minutes and s-NSCs were injected into the striatum and cortex within 2 hours post-ischemia. Brain infarct volume and neurological performance were assessed up to 28 days post-ischemia. s-NSC transplantation reduced infarct volume, improved sensorimotor and cognitive functions, and provided more robust neuroprotection than non-engineered NSCs or gal-1-overexpressing (but non-secreting) NSCs. White matter injury was also ameliorated in s-NSC-treated stroke mice. Gal-1 modulated microglial function in vitro, by attenuating secretion of pro-inflammatory cytokines (TNF-α and nitric oxide) in response to LPS stimulation and enhancing production of anti-inflammatory cytokines (IL-10 and TGF-β). Gal-1 also shifted microglia/macrophage polarization toward the beneficial M2 phenotype in vivo by reducing CD16 expression and increasing CD206 expression. In sum, s-NSC transplantation confers robust neuroprotection against cerebral ischemia, probably by alleviating white matter injury and modulating microglial/macrophage function.

Addition of autologous mesenchymal stem cells to whole blood for bioenhanced ACL repair has no benefit in the porcine model

BACKGROUND

Coculture of mesenchymal stem cells (MSCs) from the retropatellar fat pad and peripheral blood has been shown to stimulate anterior cruciate ligament (ACL) fibroblast proliferation and collagen production in vitro. Current techniques of bioenhanced ACL repair in animal studies involve adding a biologic scaffold, in this case an extracellular matrix-based scaffold saturated with autologous whole blood, to a simple suture repair of the ligament. Whether the enrichment of whole blood with MSCs would further improve the in vivo results of bioenhanced ACL repair was investigated.

HYPOTHESIS

The addition of MSCs derived from adipose tissue or peripheral blood to the blood-extracellular matrix composite, which is used in bioenhanced ACL repair to stimulate healing, would improve the biomechanical properties of a bioenhanced ACL repair after 15 weeks of healing.

STUDY DESIGN

Controlled laboratory study.

METHODS

Twenty-four adolescent Yucatan mini-pigs underwent ACL transection followed by (1) bioenhanced ACL repair, (2) bioenhanced ACL repair with the addition of autologous adipose-derived MSCs, and (3) bioenhanced ACL repair with the addition of autologous peripheral blood derived MSCs. After 15 weeks of healing, the structural properties of the ACL (yield load, failure load, and linear stiffness) were measured. Cell and vascular density were measured in the repaired ACL via histology, and its tissue structure was qualitatively evaluated using the advanced Ligament Maturity Index.

RESULTS

After 15 weeks of healing, there were no significant improvements in the biomechanical or histological properties with the addition of adipose-derived MSCs. The only significant change with the addition of peripheral blood MSCs was an increase in knee anteroposterior laxity when measured at 30° of flexion.

CONCLUSION

These findings suggest that the addition of adipose or peripheral blood MSCs to whole blood before saturation of an extracellular matrix carrier with the blood did not improve the functional results of bioenhanced ACL repair after 15 weeks of healing in the pig model.

CLINICAL RELEVANCE

Whole blood represents a practical biologic additive to ligament repair, and any other additive (including stem cells) should be demonstrated to be superior to this baseline before clinical use is considered.

Tetranuclear ruthenium(ii) complexes with oligo-oxyethylene linkers as one- and two-photon luminescent tracking non-viral gene vectors

Four tetranuclear ruthenium(ii) complexes Ru1–Ru4 based on oligo-oxyethylene and polybenzimidazole have been developed as one- and two-photon luminescent tracking non-viral gene vectors.